JP7718652B2 - How to inspect the inside of a chimney - Google Patents

Description

This disclosure relates to a method for inspecting the inside of a chimney.

A technology is known in which an aircraft such as a drone flies inside the chimney barrel, moving up and down while capturing images of the inner surface with an imaging device, and then inspections are carried out based on the captured images (see, for example, Patent Document 1).

Patent No. 6505927

The technology described in Patent Document 1 makes it possible to inspect the appearance of the inner circumferential surface based on captured images. However, images alone cannot adequately inspect, for example, the effects of corrosion on the lining material formed on the inner surface of a chimney barrel, and it is necessary to actually measure the thickness of the lining material. For this reason, there is a demand for a method that can detect the condition of the inner circumferential surface of a chimney with higher accuracy.

This disclosure has been made in light of the above, and aims to provide a chimney interior inspection method that can detect the internal condition of a chimney with high accuracy.

The chimney interior inspection method disclosed herein involves flying an aircraft equipped with an optical sensor inside the chimney, measuring the distance to the inner circumferential surface of the chimney using the optical sensor while the aircraft is flying within a specified measurement range on the inner circumferential surface, and generating a distribution map showing the distribution of irregularities within the measurement range on the inner circumferential surface based on the measurement results.

This disclosure provides a chimney interior inspection method that can detect the condition of the inner surface of a chimney barrel with higher accuracy.

FIG. 1 is a diagram showing an example of the configuration of devices and equipment used in the chimney interior inspection method according to this embodiment. FIG. 2 is a diagram showing an example of a distribution map. FIG. 3 is a cross-sectional view of the chimney shown in FIG. 1 taken along line AA. FIG. 4 is a cross-sectional view of the chimney taken along line BB in FIG. FIG. 5 is a cross-sectional view of the chimney shown in FIG. 1 taken along the line CC. FIG. 6 is a flowchart showing an example of a chimney interior inspection method according to this embodiment.

Below, an embodiment of the chimney interior inspection method according to the present disclosure will be described with reference to the drawings. Note that the present invention is not limited to this embodiment. Furthermore, the components in the following embodiment include those that are easily replaceable by a person skilled in the art, or those that are substantially identical.

Figure 1 is a diagram showing an example of the configuration of the equipment and devices used in the chimney interior inspection method according to this embodiment. In the chimney interior inspection method according to this embodiment, for example, the lining 102 applied to the inner surface 101 of the cylindrical chimney 100 is inspected for any abnormalities such as peeling, cracks, or foreign matter accumulation, and the extent of the abnormalities is photographed with a photographing device. As shown in Figure 1, the chimney interior inspection method uses an aircraft 10 and a processing device 20.

The aircraft 10 is configured to be able to fly up and down in the air inside the chimney 100. An example of an aircraft 10 is a drone. The aircraft 10 has a main body 11, a propeller 12, and a propeller drive unit 13. The propeller 12 and propeller drive unit 13 are provided on the main body 11. The propeller 12 is rotated by the propeller drive unit 13, allowing the aircraft 10 to ascend and descend inside the chimney 100. The aircraft 10 has a rotation detection sensor (not shown). The rotation detection sensor detects the horizontal orientation of the aircraft 10.

In this embodiment, the flying vehicle 10 is configured to move horizontally and vertically, for example, according to the pilot's control, but may also be configured to be capable of autonomous flight. The flying vehicle 10 takes off and lands on a takeoff and landing platform 104 located at the bottom of the chimney 100. The takeoff and landing platform 104 is located on the central axis AX of the chimney 100. Therefore, the flying vehicle 10 takes off from a position on the central axis AX and lands at a position on the central axis AX.

The aircraft 10 is equipped with an optical sensor 30. The optical sensor 30 measures the distance to an object by irradiating light onto the object, which exists in a spherical shape centered on the optical sensor 30 and is located within a distance of several tens of meters, and detecting the light scattered by the object. The detectable range of the optical sensor 30 can be the range within a sphere centered on the optical sensor 30. The sphere is set to a range larger than the diameter of the inner circumferential surface 103 centered on the central axis AX. The optical sensor 30 can measure the distance to the object as three-dimensional data.

In this embodiment, the optical sensor 30 measures the distance to the inner circumferential surface 103 of the chimney 100. The inner circumferential surface 103 includes the surface 102a of the lining 102 and the exposed portion 101a where the inner surface 101 of the barrel is exposed. The optical sensor 30 measures the distance as three-dimensional data across the entire inner circumferential surface 103 within the detectable range. If the inner circumferential surface 103 within the detectable range has irregularities, the optical sensor 30 measures the distance to the concave portions and the distance to the convex portions, respectively. In this embodiment, the optical sensor 30 measures three-dimensional distance data across a predetermined measurement range, for example, in the circumferential and vertical directions of the inner circumferential surface 103 of the chimney 100. The measurement range may be a portion or the entire inner circumferential and vertical directions of the inner circumferential surface 103.

By controlling the propeller drive unit 13 based on the measurement results of the optical sensor 30, the aircraft 10 is able to autonomously control its position and attitude inside the chimney 100 so as not to interfere with the inner surface 103.

The processing device 20 may be, for example, a personal computer. The processing device 20 has a processing device such as a CPU (Central Processing Unit) and a storage device such as a RAM (Random Access Memory) or ROM (Read Only Memory). The processing device 20 acquires three-dimensional data measured by the optical sensor 30 and calculates the distribution of irregularities on the inner circumferential surface 103 within the measurement range based on the three-dimensional data.

After generating a distribution map of irregularities in the measurement range, the processing device 20 can calculate the thickness t of the lining 102 based on the distribution map. The processing device 20 calculates the position of the central axis AX of the chimney 100, and calculates the thickness t of the lining 102 as the difference between the first distance R1, which is the distance between the central axis AX and the inner surface 101 of the barrel, and the second distance R2, which is the distance between the central axis AX and the inner circumferential surface 103.

The processing device 20 can calculate the position of the central axis AX based on the detection results of the optical sensor 30 at the exposed portion 101a of the barrel inner surface 101. The processing device 20 can also calculate the position of the central axis AX by measuring the thickness t of the lining 102 at any target position on the inner circumferential surface 103 and comparing the measurement result with the detection result of the optical sensor 30 at the target position. In this embodiment, the exposed portion 101a includes, for example, at least one of the upper edge portion 101b along the top of the barrel inner surface 101 and the manhole formation portion 105 of the chimney 100.

Next, an example of a chimney interior inspection method according to this embodiment will be described. First, an aircraft 10 equipped with an optical sensor 30 is flown inside the chimney 100, and while the aircraft 10 is flying, the optical sensor 30 measures the distance to the inner surface 103 of the chimney 100 within a predetermined measurement range of the inner surface 103. Based on the measurement results, a distribution map is generated showing the distribution of irregularities within the measurement range of the inner surface 103.

The detectable range of the optical sensor 30 in the aircraft 10 is a spherical range of several tens of meters or less, centered on the optical sensor 30. When flying the aircraft 10, the pilot lifts the aircraft 10 from a position on the central axis AX of the takeoff and landing pad 104. If there is an obstacle within the sensing distance of the spherical detectable range centered on the aircraft 10, the aircraft 10 can fly while avoiding the obstacle. Therefore, the pilot only needs to fly the aircraft 10 along the central axis AX. For example, if the aircraft 10 approaches the lining 102, the optical sensor 30 will detect the lining 102 and the aircraft will fly to avoid the obstacle, automatically avoiding interference.

The pilot then raises the aircraft 10 at a constant speed along the central axis AX. In this case, the optical sensor 30 acquires three-dimensional data in the height direction of the inner surface 103 of the chimney 100.

The processing device 20 generates a distribution map of unevenness based on the three-dimensional data measured by the optical sensor 30. The processing device 20 can display the generated distribution map on a display unit (not shown) or the like.

Figure 2 shows an example of a distribution map. As shown in Figure 2, a distribution map F of irregularities is created based on three-dimensional data in the height direction and circumferential direction of the inner circumferential surface 103. For example, in distribution map F in Figure 2, a gradation from white to black is created, with the closer to white the more convex and the closer to black the more concave. The area F1 displayed in black in Figure 2 corresponds to the manhole formation portion 105 described above.

After generating the unevenness distribution map F, the processing device 20 can calculate the thickness of the lining 102 based on this distribution map F. Figures 3 to 5 are cross-sectional views of the chimney 100 shown in Figure 1. Figure 3 shows the structure along the A-A cross section, Figure 4 shows the B-B cross section, and Figure 5 shows the structure along the C-C cross section.

As shown in Figures 3 to 5, the processing device 20 calculates the position of the central axis AX of the chimney 100, and calculates the thickness of the lining 102 as the difference between the first distance R1, which is the distance between the central axis AX and the barrel inner surface 101, and the second distance R2, which is the distance between the central axis AX and the inner circumferential surface 103. For the first distance R1, for example, the design value of the barrel inner surface 101 can be used.

The processing device 20 can also measure the thickness of the lining 102 at any target position on the inner circumferential surface 103 and calculate the position of the central axis AX by comparing the measurement result with the detection result of the optical sensor 30 at the target position. For example, by measuring the thickness of the lining 102 at a target position near the bottom of the chimney 100, which is close to the manhole formation portion 105 (see Figure 3), it is possible to easily obtain the actual measurement value.

The processing device 20 can also calculate the position of the central axis AX based on the detection results of the optical sensor 30 at the exposed portion 101a of the barrel inner surface 101. In this embodiment, the exposed portion 101a includes, for example, at least one of the portion along the top of the barrel inner surface 101 (see FIG. 5) and the manhole-forming portion 105 of the chimney 100 (see FIG. 3). At the height position shown in FIG. 4, the exposed portion 101a where the barrel inner surface 101 is exposed does not exist. Therefore, by including the exposed portion 101a in the optical sensor 30, the position of the central axis AX can be easily calculated. For example, it is sufficient to include a height position including the vicinity of the bottom of the chimney 100 as shown in FIG. 3, or a height position including the vicinity of the top of the chimney 100 as shown in FIG. 5. The position of the central axis AX can also be calculated by aligning the detection results of the optical sensor 30 at the barrel inner surface 101 with the detection results of the optical sensor 30 outside the barrel to detect three-dimensional data of the barrel outer surface at any point.

The results of detecting the exposed portion 101a by the optical sensor 30 correspond to the height position of the barrel inner surface 101 in the distribution diagram F. The thickness of the lining 102 can be considered to be the relative height position between it and the exposed portion 101a. The processing device 20 calculates a value for the distribution of unevenness based on the position of the exposed portion 101a. This calculation result corresponds to the height position (thickness) relative to the exposed portion 101a. Therefore, the processing device 20 may calculate this calculation result as the thickness of the lining 102. Similarly, the processing device 20 may calculate a value for the distribution of unevenness over the entire measurement range AR based on the actual measurement result at the target position, and calculate the thickness of the lining 102 based on the calculation result.

Figure 6 is a flowchart showing an example of a chimney interior inspection method according to this embodiment. As shown in Figure 6, first, the pilot controls the aircraft 10 to fly inside the chimney 100 (step S10). While the aircraft 10 is flying, the optical sensor 30 creates three-dimensional data based on the distance to the inner surface 103 of the chimney 100 (step S20). As the pilot ascends the aircraft 10 to the height of the chimney, the optical sensor 30 creates three-dimensional data for the entire height of the chimney 100 (step S30).

The processing device 20 generates a distribution map F showing the distribution of irregularities on the inner circumferential surface 103 based on the measurement results of the optical sensor 30 (step S40). After generating the distribution map F, the processing device 20 calculates the thickness of the lining 102 formed on the barrel inner surface 101 based on the distribution map (step S50).

As described above, the chimney interior inspection method according to this embodiment involves flying an aircraft 10 equipped with an optical sensor 30 inside the chimney 100, measuring the distance to the inner surface 103 of the chimney 100 using the optical sensor 30 while the aircraft 10 is flying, and generating a distribution diagram F showing the distribution of irregularities on the inner surface 103 based on the measurement results.

With this configuration, by generating a distribution map F of the irregularities on the inner circumferential surface 103 of the chimney 100, it is possible to easily identify depressions on the inner circumferential surface 103, i.e., areas of thinning due to corrosion, etc. This makes it possible to inspect the condition of the inner circumferential surface of the chimney 100 with a higher degree of accuracy than when inspecting an image of the inner circumferential surface 103.

In the chimney interior inspection method according to this embodiment, the chimney 100 is configured with a lining 102 formed on the barrel inner surface 101, and the thickness of the lining 102 formed on the barrel inner surface 101 is calculated based on the generated distribution map F. Therefore, it is possible to detect the thickness of the lining 102 formed on the barrel inner surface 101 of the chimney 100 with high accuracy.

In the chimney interior inspection method according to this embodiment, the inner circumferential surface 103 includes the surface 102a of the lining 102 and the exposed portion 101a where the barrel inner surface 101 is exposed. The position of the central axis AX of the chimney 100 is calculated, and the thickness of the lining 102 is calculated as the difference between the first distance R1, which is the distance between the central axis AX and the barrel inner surface 101, and the second distance R2, which is the distance between the central axis AX and the inner circumferential surface 103. Therefore, the cylindrical characteristics of the chimney 100 are utilized to calculate the position of the central axis AX, and the thickness of the lining 102 can be calculated with high accuracy based on the calculated position of the central axis AX.

In the chimney interior inspection method according to this embodiment, the thickness of the lining 102 is measured at any target position on the inner circumferential surface 103, and the position of the central axis AX is calculated by comparing the actual measurement result with the detection result of the optical sensor 30 at the target position. Therefore, by providing the actual measurement value for the relative thickness position on the inner circumferential surface 103 of the chimney 100, the thickness of the lining 102 can be efficiently calculated based on the actual measurement value.

In the chimney interior inspection method according to this embodiment, the position of the central axis AX is calculated based on the detection results of the optical sensor 30 on the exposed portion 101a. The distance between the central axis AX and the exposed portion 101a corresponds to the first distance R1. Therefore, if the measurement range AR includes the exposed portion 101a, the position of the central axis AX can be easily calculated based on the detection results of the optical sensor 30 on the exposed portion 101a.

In the chimney interior inspection method according to this embodiment, the exposed portion 101a includes at least one of the portion along the top of the barrel inner surface 101 and the portion of the chimney 100 where a manhole is formed. Therefore, if the measurement range AR includes the portion along the top of the barrel inner surface 101 and the portion of the chimney 100 where a manhole is formed, the position of the central axis AX can be easily calculated based on the detection results of the optical sensor 30 in these portions.

In the chimney interior inspection method according to this embodiment, when the aircraft 10 is flown, the attitude of the aircraft 10 is autonomously controlled using the optical sensor 30. This allows for stable measurements.

The technical scope of the present invention is not limited to the above-described embodiment, and modifications can be made as appropriate without departing from the spirit of the present invention. For example, the above-described embodiment has been described using an example of a configuration in which the aircraft 10 is not equipped with an imaging device such as a camera, but this is not limiting. For example, the aircraft 10 may be equipped with a camera. In this case, by performing measurements using the optical sensor 30 and capturing images using a camera while the aircraft 10 is flying, even higher-precision inspections can be performed.

In addition, in the above embodiment, the chimney 100 has been described as being installed so that its central axis AX is aligned vertically, but this is not limiting. The above description can also be applied to chimneys 100 that are set with their central axis AX tilted relative to the vertical.

Furthermore, in the above embodiment, an example was described in which the flying object 10 performs autonomous control, but this is not limiting. For example, a guide rope may be provided on the chimney 100, and the flying object 10 may move up and down along the guide rope.

In addition, in the above embodiment, an example was described in which a lining 102 is formed inside the chimney 100, but this is not limited to this. In a configuration in which the chimney 100 does not have a lining and the inner surface 101 of the barrel is exposed, the present invention can also be applied to measuring the thickness of the steel plate that makes up the inner surface 101 of the barrel in a state of corrosion thinning.

10 Aircraft 11 Main body 12 Propeller 13 Propeller drive unit 20 Processing device 30 Optical sensor 100 Chimney 101 Inner surface of tube body 101a Exposed portion 101b Upper edge portion 102 Lining 102a Surface 103 Inner surface 104 Landing and takeoff platform 105 Manhole formation portion AR Measurement target range AX Central axis F Distribution map F1 Region R Detectable range R1 First distance R2 Second distance

Claims (7)

Flying a flying object equipped with an optical sensor and a camera inside the chimney,
While flying the flying object, the optical sensor measures the distance to the inner circumferential surface of the chimney within a predetermined measurement range of the inner circumferential surface, and the camera captures an image of the inner circumferential surface of the chimney;
generating a distribution map showing the distribution of irregularities in the measurement range of the inner circumferential surface based on the measurement results;
The measurement target range is inspected using the distribution map and the image capture results by the camera ,
The optical sensor irradiates light in a spherical shape with the optical sensor as the center, and a range within a sphere having a diameter larger than a diameter of the inner circumferential surface and centered on the central axis of the chimney with the optical sensor as the center is set as a detectable range,
When the flying object is flown, the flying object is caused to levitate on the central axis from a point on the central axis at the bottom of the chimney, and when an obstacle is detected within the detectable range of the flying object by the optical sensor, the attitude of the flying object is autonomously controlled so as to avoid the obstacle.
How to inspect the inside of a chimney. The chimney has a configuration in which a lining is formed on the inner surface of a cylindrical body,
The chimney interior inspection method according to claim 1 , further comprising the step of calculating a thickness of the lining formed on the inner surface of the chimney body based on the generated distribution map. the inner circumferential surface includes an exposed portion where the surface of the lining and the inner surface of the cylindrical body are exposed,
The inner surface of the cylindrical body is cylindrical,
3. The chimney interior inspection method according to claim 2, further comprising the steps of: calculating a position of a central axis of the chimney; and calculating, as the thickness of the lining, a difference obtained by subtracting a second distance, which is the distance between the central axis and the inner peripheral surface, from a first distance, which is the distance between the central axis and the inner peripheral surface. 4. The chimney interior inspection method according to claim 3, further comprising measuring a thickness of the lining at an arbitrary target position on the inner circumferential surface, and calculating the position of the central axis by comparing the actual measurement result with the detection result of the optical sensor at the target position. The chimney interior inspection method according to claim 3 or 4, further comprising calculating the position of the central axis based on the detection result of the optical sensor in the exposed portion. The chimney interior inspection method according to claim 5, wherein the exposed portion includes at least one of a portion along the top of the inner surface of the barrel and a portion of the chimney where a manhole is formed. The chimney has a configuration in which no lining is formed on the inner surface of the tube body,
The chimney interior inspection method according to claim 1 , further comprising the step of calculating the thickness of the exposed portion of the steel plate that constitutes the inner surface of the chimney body based on the generated distribution map.